Shaheen al-Shami, the Fatah al-Islam commander who spoke to Al Jazeera said his men could take the battle outside the camp and accused the US of being behind the fighting.

"We understand that the army were dragged into this fight by a third party in the Lebanese government, this third party is working to implement an American plan," he said.

"The Lebanese army says they came to protect Lebanese soil and citizens but we see that certain parties within the Lebanese army are working to serve this American project."

US military aid

The US, which provided $40m in military aid to Lebanon last year, has said it was considering providing extra assistance.

Thousands of refugees have fled thecamp since a truce was declared [AFP]

"The Siniora government is fighting against a very tough extremist foe," Condoleezza Rice, US secretary of state, said.

"But Lebanon is doing the right thing to try to protect its population, to assert its sovereignty and so we are very supportive of the Siniora government and what it is trying to do."

The Palestine Liberation Organisation has said it would not object if the army sent troops into the Nahr al-Bared to root out the fighters despite a forty-year-old agreement not to interfere in the refugee camps.

"This is a Lebanese decision, this is Lebanon's decision," Abbas Ziki, the PLO representative in Lebanon, said.

"We have declared that the country is for Lebanon and sovereignty is for Lebanon, and whatever Lebanon decides or considers its higher interests, we support it."